Obstructive sleep apnea (OSA) is a common disease that is largely under-diagnosed and untreated. Nasal continuous positive airway pressure (CPAP) is the standard treatment for OSA. CPAP entails use of a nose mask to deliver positive pressure, which dilates a subject's pharynx and eliminates obstruction. This therapy is highly efficacious and benign but is associated with low adherence in many subjects, particularly those with disease of mild and moderate severity. The principal alternative to CPAP therapy is oral appliance (OA) therapy in which a custom made mandibular repositioner (MR) is used to protrude the subject's mandible during sleep, thereby opening the subject's pharyngeal airway. OA therapy, while preferred and well accepted by most subjects, is not uniformly effective in eliminating sleep apnea.
The effectiveness of OA therapy can be improved by screening OSA subjects and prospectively identifying those suitable for this therapy. Studies of the passive pharynx indicate that the response of the pharynx to mandibular protrusion is dose dependent. In other words, incremental mandibular protrusion produces corresponding pharyngeal enlargement. However, clinical experience shows that excessive mandibular protrusion is undesirable, producing side effects, such as, pain and tooth movement that lead to discontinuation of therapy. In some cases, over-protrusion can worsen OSA. According to current practice, a treatment provider such as a dentist progressively protrudes the subject's mandible until a symptomatic response occurs. The subject is then reassessed to determine if OSA has resolved.
Prospective identification of suitable candidates, as well as target effective protrusion levels, can greatly facilitate treatment of OSA with OA therapy. U.S. Pat. No. 5,826,579 to Remmers et al., entitled “Remote-Controlled Mandibular Positioning Device and Method of Using the Device,” which is incorporated herein in its entirety by reference, describes a remotely-controlled mandibular positioner (RCMP). Additionally, U.S. Pat. No. 6,273,859 to Remmers et al., entitled “Adaptively Controlled Mandibular Positioning Device and Method of Using the Device,” which is incorporated herein in its entirety by reference, describes an OA therapy which is an automatically-controlled mandibular positioner (ACMP).
Conventionally, the overall approach to the titration for OA therapy is to evaluate the physiological response (e.g., respiratory events such as apneas, hypopneas, snoring etc. and/or evidence of obstructions) at discrete levels mandibular protrusion. For example, the level of protrusion is maintained constant all night and therapeutic effectiveness can be assessed offline at the end of the night (e.g., using conventional home monitors). Alternatively, therapeutic effectiveness is assessed offline by evaluating the physiologic response at various levels of protrusion that are collected during a polysomnographic study during which a technician either manually (e.g., at the MR) or remotely (e.g., using the RCMP) adjusts an MR. In addition, when providing OA therapy, the level of protrusion can be held at the level of protrusion determined to be therapeutically effective, or it can be automatically adjusted in response to evidence of obstruction (e.g., using the ACMP).